The Aletsch Glacier is the largest glacier in the Alps. It has a length of about 23 km and covers more than 120 square kilometres in the eastern Bernese Alps in the Swiss canton of Valais. The whole area, including other glaciers is part of the Jungfrau-Aletsch Protected Area, which was declared a UNESCO World Heritage site in 2001.
The Aletsch Glacier is one of the many glaciers located between the cantons of Berne and Valais on the Bernese Alps located east of the Gemmi Pass. The whole area is considered to be the largest glaciated area in western Eurasia. The Fiescher and Aar glaciers lying on the east have similar extensions.
Except the Finsteraarhorn, all the highest summits of the Bernese Alps are located within the drainage basin of the glacier. The Jungfrau and Mönch constitute the northern boundary; the Gross Fiescherhorn and Gross Wannenhorn lie on its east side; finally the culminating point, the Aletschhorn (4,195 meters) is located on the west side. From the western mouth flows the Great Aletschfirn, which runs along the northern foot of the Aletschhorn and Dreieckhorn. The Aletschfirn is supplied from the north by three notable firns: the Ebnefluhfirn, the Gletscherhornfirn, and the Kranzberfirn. All of these Firns have their starting points at around 3800 m.
Source: en.wikipedia.org/wiki/Aletsch_Glacier – 20.11.2008